diff --git a/oryx/core/interpreters/harvest.py b/oryx/core/interpreters/harvest.py
index 6d4d4ca..3e1beca 100644
--- a/oryx/core/interpreters/harvest.py
+++ b/oryx/core/interpreters/harvest.py
@@ -1211,14 +1211,14 @@ def _calc_extra_inps(num_consts, params):
 def _reap_pjit_rule(trace, *tracers, **params):
   """Reap pjit rule."""
   if params['in_shardings'] and not any(
-      sharding_impls.is_unspecified(i) for i in params['in_shardings']
+      isinstance(i, sharding_impls.UnspecifiedValue) for i in params['in_shardings']
   ):
     raise ValueError(
         'oryx only supports pjit which has no in_axis_resources '
         f'specified. Got {params["in_shardings"]}'
     )
   if params['out_shardings'] and not any(
-      sharding_impls.is_unspecified(o) for o in params['out_shardings']
+      isinstance(o, sharding_impls.UnspecifiedValue) for o in params['out_shardings']
   ):
     raise ValueError(
         'oryx only supports pjit which has no out_axis_resources '
@@ -1648,14 +1648,14 @@ def _plant_checkpoint_rule(trace, *tracers, jaxpr, policy, prevent_cse,
 def _plant_pjit_rule(trace, *tracers, **params):
   """Plant pjit rule."""
   if params['in_shardings'] and not any(
-      sharding_impls.is_unspecified(i) for i in params['in_shardings']
+      isinstance(i, sharding_impls.UnspecifiedValue) for i in params['in_shardings']
   ):
     raise ValueError(
         'oryx only supports pjit which has no in_axis_resources '
         f'specified. Got {params["in_shardings"]}'
     )
   if params['out_shardings'] and not any(
-      sharding_impls.is_unspecified(o) for o in params['out_shardings']
+      isinstance(o, sharding_impls.UnspecifiedValue) for o in params['out_shardings']
   ):
     raise ValueError(
         'oryx only supports pjit which has no out_axis_resources '
diff --git a/oryx/core/interpreters/propagate.py b/oryx/core/interpreters/propagate.py
index bcf5b3b..7b0a84b 100644
--- a/oryx/core/interpreters/propagate.py
+++ b/oryx/core/interpreters/propagate.py
@@ -38,7 +38,6 @@
 from jax._src import sharding_impls
 from jax.extend import linear_util as lu
 from jax.interpreters import partial_eval as pe
-from jax.interpreters import pxla
 
 from oryx.core import pytree
 from oryx.core import trace_util
@@ -367,10 +366,10 @@ def _pjit_propagate_rule(incells, outcells, **params):
   """Propagate rule for pjit primitive."""
   # TODO(https://github.com/jax-ml/oryx/issues/29): Fix this rule so that it  # pylint: disable=g-bad-todo
   # works correct for in_sharding, out_shardings and donated_invars.
-  if not any(pxla._is_unspecified(i) for i in params['in_shardings']):  # pylint: disable=protected-access
+  if not any(isinstance(i, sharding_impls.UnspecifiedValue) for i in params['in_shardings']):  # pylint: disable=protected-access
     raise ValueError('oryx only supports pjit which has no in_axis_resources '
                      'specified.')
-  if not any(pxla._is_unspecified(o) for o in params['out_shardings']):  # pylint: disable=protected-access
+  if not any(isinstance(o, sharding_impls.UnspecifiedValue) for o in params['out_shardings']):  # pylint: disable=protected-access
     raise ValueError('oryx only supports pjit which has no out_axis_resources '
                      'specified.')